A spate of lab-associated Salmonella infections has swept across the United States during the past year, prompting public-health officials to examine how closely labs are following infection-prevention protocols.

"The fact that cases seem to be happening all over the country has raised the question of whether there are issues with laboratory safety and appropriate training techniques," says Mack Sewell, state epidemiologist at the New Mexico Department of Health in Santa Fe.

Between August 2010 and March this year, 73 infections due to Salmonella typhi­murium, a relatively common strain of the bacterium, caused illness in people across 35 states and one death, the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, reported on 28 April. The outbreak now seems to have ended, with the number of reported new infections dropping to the usual baseline of 0–4 per week, the CDC says.